Asymmetric drive motor for a barrier operator or the like

ABSTRACT

An asymmetrical drive motor and apparatus with the asymmetric drive motor driving a barrier. The asymmetric drive motor drives the barrier at different drive powers according to direction, time of travel, safety requirements or speed. The drive power is controlled by electrically changing the capacitance value for a permanent split capacitor motor.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention is related to a movable barrier and moreparticularly, to a motor for driving a movable barrier such as a garagedoor.

[0003] 2. Background Description

[0004] Movable barrier operators and, more particularly, garage dooroperators are well known and have become very sophisticated to provideusers with increased convenience and security. The amount of drive powerfor such a barrier operator is usually selected based on a trade offbetween the need for power to start and continue the door's motion andthe noise and vibration generated by the motor, as well as theavailability of electrical power. Generally, it is desirable to have ahigher power to open the door due to ice and snow freezing the doordown. Also, during safety initiated operations larger amounts of powermay be desired to reverse or stop the barrier. A problem is that ahigher power motor usually create larger levels of noise and vibrationand require more electrical power and thus, generate more heat tooperate for the same level of mechanical power.

[0005] For example, in a situation where the door has become extremelyheavy such as when the door's counter balance spring has broken and thedoor is required to reverse, a low power motor which is adequate to keepa door in motion may not have enough power to overcome both the inertiaof motion and the extreme weight of the door. Typically, in selecting adrive motor for a barrier operator, safety takes precedence over noiseand vibration or operational electrical efficiency and, the motor isselected to open the garage door in all situations.

[0006] By contrast selecting a high power motor allows the operator tohave enough power to lift the door even when the door's spring hasbroken. In this situation the high power operator has the ability toopen the door but is often more inefficient and has higher levels of,noise and vibration.

[0007] The typical motor used in such a garage door operators is asingle phase motor. A single-phase motor may be classified as a splitphase motor, a permanent split capacitor (PSC) motor, a capacitorstart-induction run motor or a capacitor start-capacitor run motor.Further, most single-phase induction motors require a switchingarrangement for starting the motor, e.g., switching start windings, astart capacitor, a run capacitor or a combination thereof, to assist themotor in reaching full speed. Capacitor start motors have a startcapacitor that is only used to start the motor.

[0008] Thus, there is a need for a motor than can have higher powerduring intervals that require it, yet switch to a lower power, to reduceelectrical power requirement and noise and vibration.

SUMMARY OF THE INVENTION

[0009] The present invention is an asymmetric drive motor and apparatuswith the asymmetric drive motor for opening and closing a moveablebarrier. The asymmetric drive motor may drive for example, a garage dooropen at a first drive power and closed at a second drive power. Thefirst drive power is greater than the second drive power. A motorcontrol circuit receives control commands and controls the motor toprovide the first drive power if barrier is being opened and at thesecond drive power if the barrier is being closed.

[0010] Accordingly, the asymmetric motor of the present invention hasimproved power control for selecting higher power or lower power.Further, momentary application of higher power is available if needed atthe start of travel for example to overcome inertia or ice that may havefrozen the barrier shut. In emergency situations such as when thebarrier has encountered an object on closing higher power is availableto quickly open the barrier. Further, a power can be adjusted in themotor depending on the load driven by the motor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The foregoing and other objects, aspects and advantages will bebetter understood from the following detailed preferred embodimentdescription with reference to the drawings, in which:

[0012]FIG. 1 shows an example of a movable barrier operator or garagedoor operator (GDO) according to the present invention;

[0013]FIG. 2 shows a first preferred embodiment of asymmetric drivemotor according to the present invention, which acts as a hybridpermanent split capacitor/capacitor start single phase motor with morepower in one direction than in an opposite direction;

[0014]FIG. 3 is a second preferred embodiment asymmetric drive garagedoor motor which is substantially similar to the embodiment of FIG. 2;

[0015]FIG. 4 is a third preferred embodiment asymmetric drive motorsubstantially similar to the first two embodiments of FIGS. 2 and 3 withlike elements labeled identically;

[0016]FIG. 5 is an example of a controller controlling an asymmetricdrive motor such as in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Referring now to the drawings, and more particularly, FIG. 1shows an example of a movable barrier operator or garage door operator(GDO) according to the present invention, generally referred to bynumeral 100. The preferred GDO 100 includes a preferred embodimentasymmetric drive motor 150 (FIG. 5) and a control circuit 208 (FIG. 5)controlling GDO operation in a head unit 102 that is mounted to theceiling of a garage 104. A rail 106 extends from the head unit 102. Atrolley 108 is releasably attached to the rail 106 and includes an arm110 extending to a multiple paneled garage door 112 positioned formovement along a pair of door rails 114 and 116. The GDO system 100includes at least one hand-held remote control transmitter unit 118adapted to send signals to an antenna 120 on the head unit 102. Signalsfrom the antenna 120 are provided to the control circuit in the headunit 102. An external remote control pad 122 is positioned on theoutside of the garage and includes multiple buttons thereon forcommunicating via radio frequency transmission with the control circuitin the head unit 102. A wall switch module 124 is mounted on a wall ofthe garage. The wall switch module 124 is a wired remote controlconnected to the control circuit in the head unit 102 by a wire 126. Thewall switch module 124 may include a light switch 130, a lock switch 132and a command switch 134. An optical emitter 138, preferably emitting aninfrared (IR) beam, is connected via a power and signal line 140 to thecontrol circuit in the head unit 102. An optical detector 142, disposedopposite the optical emitter 138 and receiving the IR beam, also isconnected by a wire 144 to the control circuit in the head unit 102. Theoptical detectors 133 and 142 serve to sense if an obstruction ispresent in the barrier opening.

[0018]FIG. 2 shows a first preferred embodiment of asymmetric drivemotor 150 according to the present invention, which acts a hybridpermanent split capacitor/capacitor start single phase motor with moreor less drive power being selected by a controller of head unit 102. Themotor 150 includes two coils or windings 152, 154 in the stator. Thecommon connection of the two windings 152 and 154 is connected to groundor a neutral reference voltage terminal. Capacitor 158 is permanentlyconnected across terminals at the opposite ends of the two windings 152,154. A second capacitor 160 and parallel bleed resistor 162 are seriesconnected with a relay 164 across first capacitor 158. Line current isprovided through a light relay 166 to a direction relay 168 whichselectively passes line current directly to either side of capacitor 158and one of windings 152, 154. In this embodiment providing line currentto winding 152 drives the garage door operator in the up direction. Downrelay 170 passes line current to the motor at winding 154 only when themotor is driving the garage door down to close it.

[0019] When the garage door operator is activated to drive the doordown, e.g., by pressing a button on a remote; the control circuit closeslight relay 166; direction relay 168 remains in the position shown ofFIG. 2; down relay 170 is closed; and, higher power relay 164 remains inits open position as shown in FIG. 2. Alternating line current isprovided to coil 154 at capacitor 158. Capacitor 158 passes a currentout of phase with the line current to coil 152. As a result, the motor150 drives the garage door down at a first drive power level, e.g., ½horsepower (hp). When the garage door is operator is activated, again,the control circuit closes light relay 166. However, direction relay 168switches to the up position, down relay 170 remains open as shown inFIG. 2 and high power relay 164 is closed. Since directional relay is inthe up position, line current is provided to coil 152 at capacitor 158and capacitor 158 provides a current out of phase with the line currentto inductor 154. With higher power relay 164 closed, effectively,capacitors 158 and 162 are in parallel to increase the drive power ofthe motor, e.g., from ½ hp to ¾ hp. Thus, the motor 150 drives thegarage door open with 50% more power than is available for driving thegarage door closed.

[0020] The control circuit may be programmed to keep the high powerrelay 164 closed for substantially the entire travel of the garage door,keep the high power relay 164 closed for a period of time or, asdetermined by the sensed speed of the motor 150. Thus, the high powerrelay 164 may be closed for a period of time to initially open thegarage door. When the high power relay 164 opens, bleed resistor 162discharges any charge remaining on second capacitor 160. Alternately,the control circuit 200 (FIG. 5) which includes a motor rotation sensor226 may sense motor speed and keep the high power relay closed when thedoor is opening and until the motor reaches a pre-selected speed for astart capacitor-like operation. Also, in emergency situations, e.g.,when an object is encountered by the closing garage door or anobstruction is sensed by optical detectors the controller may reversethe travel of the door. At such direction reversal the high power relay164 is activated when the motor 150 reverses to drive the motor at highpower for opening the garage door to recover from the emergency. Inaddition, the high power relay 164 may be closed to recover from afalling door situation, i.e., when the control circuit detects the dooris falling, the motor is activated to keep it from hitting the floor.

[0021]FIG. 3 is a second preferred embodiment asymmetric drive garagedoor motor 180 which is substantially similar to the embodiment of FIG.2. Accordingly, in FIG. 3 like elements are labeled identically. In thisembodiment the second capacitor 182 and parallel bleed resistor 184 areseries connected with higher power relay 186 across the direction relay168 and down relay 170. Since the higher power relay 186 is energizedwhen the motor 180 is raising the garage door, operation issubstantially identical to the above description for operation of themotor 150 of FIG. 2, especially for lowering the garage door. When thedoor is closed and a button on a remote is pressed to cause the controlcircuit to activate the motor to open the door, the control circuitcloses light relay 166 and switches direction relay 168 in its upposition; down relay 170 remains open; and, high power relay 184 isclosed. Again, with both the high power relay 186 closed and thedirection relay 168 in its up position, the second capacitor 180 isessentially in parallel with the first capacitor 158, boosting power ofthe motor substantially as in the embodiment of FIG. 2. When higherpower relay 184 is opened, any remaining charge across second capacitor180 discharges through bleed resistor 182. With this embodiment also,the higher power relay 184 may be closed then opened again at thebeginning of the opening door travel or during an emergency situation.Alternately, higher power relay 184 may be held on until the motor 180reaches a selected minimum speed.

[0022]FIG. 4 is a third preferred embodiment asymmetric drive motor 190substantially similar to the first two embodiments of FIGS. 2 and 3 withlike elements to FIG. 2 labeled identically. In this embodiment both thefirst capacitor 192 and the second capacitor 160 are switched in bypower relays 196 and 164, respectively. Each capacitor 192, 160 has aparallel respective bleed resistor 194, 162. Thus, this embodiment hasthree selectable drive power levels determined by the first capacitor192, the second capacitor 160 and the sum of the two capacitors 160,192. The power level is selected by closing the appropriate one of powerrelay 164, 196 or the combination thereof. This embodiment may provideincreased power on demand, e.g., selecting both capacitors 160, 192 wheninitially opening the garage door. Also, power can be controlled andprovided as needed, e.g., when one capacitor 160 or 192 is switched inand the control circuit detects that the garage door is slowing down,the other capacitor 192, 160 may be switched in or substituted to boostmotor drive. In response to the additional drive power, the drive motor190 drives the door back to the minimum speed and then reduces power byopening one of switches 164 and 192.

[0023]FIG. 5 is an example of a controller 200 controlling an asymmetricdrive motor 150 such as in FIG. 2. The controller 200 is powered by apower supply 202 that converts alternating current from an alternatingcurrent source, such as 110 volt AC, to required levels of DC voltage.The controller 200 is mounted in the head unit, e.g., head unit 102 ofFIG. 1, with antenna 120 attached to receiver 204 which is coupled via aline 206 to supply demodulated digital signals to a microcontroller 208.The microcontroller 208 is also coupled by a bus 210 to a non-volatilememory 212, which stores user codes, and other digital data related tothe operation of the control unit 200. Emitter 138 and infrared detector142 form an obstacle detector 214 and power and signal lines 140, 144form an obstacle detector bus 216 connected to microcontroller 208. Theobstacle detector bus 218 includes lines 140 and 144. The wall switchmodule 124 is connected via wire 126 to the microcontroller 208. Themicrocontroller 208, in response to switch closures and received codes,sends signals over a relay logic line 220 to a relay logic module 222connected to asymmetric drive motor 150 which has a power take-off shaft(not shown) from the rotor coupled to the transmission of the garagedoor operator 100 of FIG. 1. A tachometer 226 is coupled to theasymmetric drive motor 150 and provides an RPM signal on a tachometerline 228 to the microcontroller 208; the tachometer signal provides anindication of the speed at which the door is being driven. The apparatusalso includes up and down limit switches 230, respectively sensing whenthe door 112 is fully open or fully closed. The limit switches 230 areconnected to microcontroller 208 by leads 232. A light 234 is controlledby microcontroller 208 through logic module 222.

[0024] Accordingly, the asymmetric motor of the present invention hasimproved power control for selecting higher power or lower powerdepending on a direction of travel of the garage door. Further,momentary application of higher power is available if needed at thestart of travel for example to overcome inertia or ice that may havefrozen the garage door shut. Higher power is available in emergencysituations such as when the door has encountered an object on closing,higher power is available to quickly open the door. Further, a power canbe adjusted in the motor depending on the load driven by the motor anddepending on the sensed speed of the motor. In the preceding embodimentsthe switches for controlling motor activation are shown as relays. Suchrelays may be replaced by other devices such as semiconductor triacs inother embodiments.

[0025] The embodiments described include a motor having a pair ofwindings with a neutral tap at a common winding terminal. The controlprinciples discussed herein are not limited to such a windingconfiguration, but may apply to any motor configuration capable ofproducing two or more levels of power output. For example, but not bylimitation, the motor could comprise multiple serially energizedwindings which can be individually removed from providing substantialmotive force by switching arrangements such as by shorting across theterminals of individual windings. Further, the increase of power outputas well as phase shifting could be performed by reactive componentsother than capacitors, such as inductors.

[0026] Having thus described preferred embodiments of the presentinvention, various modifications and changes will occur to a personskilled in the art without departing from the spirit and scope of theinvention. It is intended that all such variations and modificationsfall within the scope of the appended claims. Examples and drawings are,accordingly, to be regarded as illustrative rather than restrictive.

What is claimed is:
 1. A motor for driving a movable barrier operator,said motor comprising: a rotor; a stator, said stator comprising a firstwinding and a second winding, said first winding and second windingconnected at one end to a neutral motor terminal; a first capacitorcoupled across winding terminals at an other end of each of said firstwinding and said second winding; a direction control selectively passingalternating current (AC) to either side of said first capacitor; and asecond capacitor selectively coupled across said first capacitor when ACis provided to one side of said first capacitor and disconnected fromsaid first capacitor when AC is provided to a second side of said firstcapacitor to control the amount of power delivered by the motor.
 2. Amotor in accordance with claim 1 comprising apparatus for sensing motorspeed and a controller responsive to the sensed motor speed forcontrolling the selective coupling of the second capacitor.
 3. A motorin accordance with claim 1 comprising apparatus for sensing thedirection of the travel and for controlling the selective coupling ofthe second capacitor.
 4. A motor in accordance with claim 1 comprisingapparatus for sensing a time for which the motor has been in motion anda controller is responsive to the sensed time for controlling theselective coupling of the second capacitor.
 5. A motor in accordancewith claim 1 wherein the motor is connected to move a barrier andcomprising an apparatus for sensing a distance of travel of the barrierand a controller for controlling the selective coupling of the secondcapacitor according to the distance of travel.
 6. A motor as in claim 1further comprising: a light relay selectively passing AC to saiddirection controller when said motor is energized; and said directioncontroller passing AC from said light relay to a selected one of saidone side and said second side of said first capacitor.
 7. A motor as inclaim 6 further comprising: a down relay connected between saiddirection relay and said second side, said down relay passing current tosaid second side of said first capacitor when said down relay isenergized; and a higher power relay series connected with said secondcapacitor,
 8. A motor as in claim 7 further wherein: said higher powerrelay and said down relay are energized mutually exclusively.
 9. A motoras in claim 8 wherein said down relay is connected between saiddirection controller and said second side of first capacitor, said highpower relay and said direction controller being coupled to said one sideof said first capacitor.
 10. A motor as in claim 9 wherein said firstcapacitor is series connected at said one side with a second high powerrelay and further including a bleed resistor parallel connected witheach of said first capacitor and said second capacitor, wherein at leastone of said down relay, the first said high power relay and said secondhigh power relay always being de-energized.
 11. A motor as in claim 9wherein one end of said series connected high powered relay and saidsecond capacitor is connected between said light relay and saiddirection controller and to said second end of said first capacitor. 12.A movable barrier operator including a motor as in claim 1, whereby saidmotor provides power at a first drive power level for driving saidmovable barrier operator into a first open position and at a seconddrive power level for driving to a closed position, said first drivepower level being greater than said second drive power level.
 13. Anapparatus for opening and closing a garage door comprising: anasymmetric drive motor driving a garage door open at a first drive powerand closed at a second drive power; and, a motor control circuitselecting drive power for said asymmetric drive motor responsive to doorcontrol commands and an indication that said garage door is being openedor closed, said first drive power being greater than said second drivepower.
 14. An apparatus as in claim 13 wherein said asymmetric drivemotor comprises: a rotor; a stator, said stator comprising a startwinding and a drive winding, said start winding and drive windingconnected at one end to a neutral motor terminal; a first capacitorcoupled across winding terminals at an other end of said start windingand said drive winding; a direction switch selectively passingalternating current (AC) to either side of each of said first capacitorresponsive to said motor control circuit; and a second capacitor coupledacross said first capacitor to select said first drive power, AC beingprovided to one side of both said first capacitor and said secondcapacitor, responsive to said motor control circuit.
 15. An apparatus asin claim 14, said asymmetric drive motor further comprising: a lightrelay selectively energizing a light and passing AC to said directionrelay when said motor is energized responsive to said motor controlcircuit; said direction switch passing AC from said light relay to aselected one of said one side and a second side of said first capacitorresponsive to said motor control circuit, said second capacitor beingdisconnected when AC is passed to said second side.
 16. An apparatus asin claim 15 further comprising: a down relay connected between saiddirection relay and said second side, said down relay passing current tosaid second side of said first capacitor when said down relay isenergized: a high power relay series connected with said secondcapacitor, said motor control circuit mutually exclusively energizingeither of said higher power relay and said down relay.
 17. An apparatusas in claim 15 wherein said down relay is connected between saiddirection relay and said second side of said first capacitor, saidhigher power relay and said direction relay being coupled to said oneside of said first capacitor.
 18. An apparatus as in claim 17 whereinsaid first capacitor is series connected with a second higher powerrelay, and further including a bleed resistor parallel connected witheach of said first capacitor and said second capacitor, said motorcontrol circuit maintaining at least one of said down relay, the firstsaid higher power relay and said second higher powered relaydeenergized.
 19. An apparatus as in claim 17 wherein one end of saidseries connected high powered relay and second capacitor are connectedat one end to said light relay and said direction relay and at anotherend to said second end of said first capacitor.
 20. An apparatus as inclaim 13 further comprising a sensor sensing garage door rate of travel.21. A barrier movement arrangement comprising: a motor having a firstpower output and a second power output, for moving a barrier betweenopen and closed positions; first apparatus for enabling the first poweroutput; second apparatus for enabling the second power output, thesecond power output being greater than the first; and a controllerresponsive to sensed barrier movement conditions for controlling thefirst apparatus to enable the motor at the first power output whenpredetermined conditions are sensed and for controlling the secondapparatus to enable the motor at the second power output whenpredetermined other conditions are sensed.
 22. A barrier movementarrangement in accordance with claim 21 comprising apparatus for sensingexpected barrier movement direction and wherein the controller respondsto the sensed condition that a barrier is to be moved toward the openposition for controlling the second apparatus to enable the motor at thesecond power output.
 23. A barrier movement arrangement according toclaim 21 comprising apparatus for sensing an expected direction ofbarrier movement and wherein the controller responds to a sensedcondition that the barrier is to be moved toward the closed position forcontrolling the first apparatus to enable the first power output tostart and move the door.
 24. A barrier movement arrangement according toclaim 21 comprising the ability to sense obstructions to barriermovement wherein the controller responds to sensed obstructions byreversing a direction of travel of the barrier and by controlling thesecond apparatus to enable the motor at the second power output.
 25. Abarrier movement arrangement according to claim 21 comprising theability to sense barrier movement speed after the motor has been startedand the controller responds to barrier movement speed after the motorhas been started to control the second apparatus to enable the motor atthe second power when the sensed barrier movement speed is below apredetermined value.